Hydro-refining method for lubricating oils and wax using nickel molybdate or silver molybdate on alumina



United States Patent HYDRO-REFINING METHOD FOR LUBRICATING OILS AND WAXUSING NICKEL MOLYBDATE OR SILVER MOLYBDATE 0N ALUlVIINA Weldon G.Annable, Crystal Lake, and William Jacobs, Mundelein, Ill., assignors toThe Pure Oil Company, Chicago, 111., a corporation of Ohio No Drawing.Application May 25, 1956 Serial No. 587,221

6 Claims. (Cl. 20827) This invention relates to a method of refining orfinish-treating lubricating oils, waxes and their fractions byhydrogenation. under specific mild conditions in the presence of acatalyst comprising silver molybdate and/ or nickel molybdate. Moreparticularly, this invention relates to a method of decolor'izing andstabilizing lubricating oils and waxes and their semi-finished fractionswithout affecting the other properties thereof by treatment withhydrogen at 450 to 650 F., 150 to 1000 lbs. per square inch pressure,using hydrogen circulation rates of 800 to 4000 s.c.f./bbl. in thepresence of a catalyst comprising 2 to 30 weight percent of silvermolybdate or nickel molybdate or mixtures thereof supported on alumina.H I

It is known in the art that the heavier fractions of crude 'oil,such,a's lubricating oils and waxes and their fractions are enhanced inutility and stability by refining through both chemical and physicalmeans. Lubricating oils and waxes are commonly subjected to varioustreatments for the purpose of increasing their stability during Iportant, producing good yields of finished products which haveacceptable color, odor and general appearance. It is essential thatthese refined products retain their enhanced and augmented propertiesafter they leave the which is applicable to lubricating oilsandwaxes andtheir fractions wherein the above objectives may be accomplished.

The art teaches that various addends may be incorporated in refinedpetroleum products to overcome shortcomings in inherent properties,further augment desirable physical and chemical properties, and bringabout new properties. Because of their cost, the necessity of closecontrol of their use, differences in effectiveness and the desirabilityof attaining a stable and uniform level of good oxidation resistance, orcolor, or viscosity or other properties in the product, it is equallydesirable that the use of additives be minimized or eliminated. Anotherobject of this invention is to provide a process for finishinglubricating oils and waxes and their fractions which; in whole or inpart, eliminates the necessity of further fortification by the use ofadditives.

It is also recognized in the art that only through judicious applicationof refining methods can the inherent stability, color properties, orviscosity temperature properties of a lubricating oil or wax bemaintained, since many refining operations, including acid treatment,hydrogenation, solvent extraction, adsorption, thermal diffusion,extractive distillation, chemical and clay treatice ments, removedesirable constituents as well as undesirable constituents. The higherfractions of petroleum contain the more complex hydrocarbons along withvarious significant amounts of oxygen, sulfur and nitrogen compounds.This means that removal or transformation of one or more of these typesof compounds may bring about a desirable change in the finished productfor one purpose and a highly undesirable change for another purpose. Theoxidation-inhibiting properties of the naturally occurring sulfurcompounds is a good example of this phenomenon, for which there is ampleevidence and considerable discussion in the prior art. A lubricating oilwhich has been severely refined to a very low sulfur content is not asstable to oxidation, nor as resistant to wear, as the same oil which hasnot been as severely refined and which contains small amounts ofresidual, naturally occurring sulfur compounds. Nitrogen and oxygencompounds have similar but lesser effects, although certain naturalacidic or phenolic bodies have been shown to be exceptions to this rule.The natural sulfur compounds seem to be the principal agents responsiblefor the stability of straight mineral lubricating resistance tooxidation, 'or resistance ,to emulsification,

that may b'e'p'rese'rit in a refined oil or wax ready for finishing oi"'d'ecolorization, this invention provides a finishing step which doesnot deleteriously effect any inherent stability or other desirableproperty. A further object of the invention is to provide a refining orfinishing process for lubricating oils and waxes involving mildhydrogenation under certain conditions using a particular catalyst;

it is well known in the art that oils and waxes may be beneficiated bytreatment at elevated temperatures withhydrogen using catalysts known topromote thehydrogenation reaction. For this purpose the art lists alarge number of metal compounds, particularly the oxides and sulfides ofgroup VI and group VIII metals, paying particular attention tochromium,.molybdenum, tungsten, iron, cobalt, and nickel. Manyreferences are made to the use of oxides of molybdenum, either alone oradmixed with other components, such as alkali metals, alkaline earthmetals, oxides and sulfides; these are promoted with iron, cobalt ornickel for the purpose of hydrogenating organic materials. Mixtures ofoxides and molybdenum oxide are used to promote the hydrogenation ofglyceride oils. In the prior art investigations molybdate salts ofvarious metals are designated as superior hydrogenation catalysts. Thepresent invention is based upon the finding that for the purpose ofdecolorizing and stabilizing lubricating oils and waxes withoutdeleteriously affecting the other properties thereof, silver molybdateand nickel molybdate are outstanding in their properties and are not theequivalent of the large group of catalytic materials disclosed in theprior art.

Accordingly, it becomes a primary object of this invention to provide aprocess for the refining of lubricating oils, waxes and their fractionsunder certain mild conditions of hydrogenation using silver molybdateand/or nickel molybdate as the promoting material.

A second object of this invention is to provide a process fordecolorizing lubricating oils and waxes by hydrogenation at 450 to 650F. in the presence of a silver molybdate-alumina catalyst and/ or anickel molybdate-alumina catalyst.

A third object of this invention is to provide a process fordecolorizing lubricating oils and waxes in high yields withoutdeleteriously affecting such properties as viscosity, viscosity index,gravity, emulsibility, penetration and general stability during use andduring storage.

A further object of this invention is to provide a process fordecolorizing and finish-treating lubricating oils and waxes possessingnatural resistance to oxidation and deterioration under conditions suchthat these inherent stability properties of the oils and waxes, orfractions of temperatures, on the other hand is an efiectivedecolorizing agent and silver molybdate carries the ASTM color down to+3. Furthermore, it is apparent that the other product characteristicsof the finished oil, such as VI, gravity, steam emulsion number areequivalent to, if not better than, those produced by the commercialcatalyst or cobalt molybdate. In finishing lubricating oils the color ofthe hydrogenated product will vary somewhat with the grade of neutraloil. Light neutrals should have an ASTM color of about 1, while brightstocks should have an ASTM color of about 5, with the other neutralshaving colors between these two extremes.

The problem of improving the color of waxes, particularlymicrocrystalline wax, is more difiicult than improving the color oflubricating oils. Clay contacting or other contacting methods arecapable of producing ASTM colors slightly darker than 1 to meet a colorspecification of 2. Careful control of the contacting method may bringabout a product color of about 1 /z+. Percolation methods SAE 30 oil:are not capable of yielding products which meet these C n COHTadSOH,Welght Pcfcellt 0- color specifications. The invention is furtherillustrated Color, ASTM (NPA) 4% by reference to the data in Table IIshowing the results Flash, C.O.C., F 445 obtainable in hydrogenatingmicrocrystalline wax having Fire, C,O.C., F. 95 the followingcharacteristics:

Flash, f; 435 Color, ASTM (NPA) +4 /2 VlS. SUS at 100 F., secs 604 M I oetmg point, P 179 vlS, at F-, Se s P t t 770 F 1 Vis sus at 210 F. secs67.9 ene fa 3 a 7 d 93 Penetration at 100 F 27 9 ex Penetration at l20 F84 Gravlty: 6 30 Total sulfur weight percent 014 Refractlve Index, N /D1-4 Bromine number 1.6 This microcrystalline wax was obtalned fr m aMid.c Total lfu weight percent 0.67 tinent residuum having the followingcharacteristics: boils Steam emulsion number 792 a ove a o SUS t 2 39 1,

TABLE I Hydrotreating SAE 30 base oil Reaction Conditions ProductCharacterlstles Exp.

No. Catalyst H Car- Vie. Vls. Vls. Steam Temp., Press, LVHSV Rate, bonColor Flash, Fire, at at at V.L. Grav., RJI. Br. Tot. Emu]. F. p.s.l.g.ftJ/bbl. Res. 000 000 210 API .010. $1111. No.

(STP) F. F. F.

11" 550 250 1.0 5,700 4 400 510 1.4020 2 0 llzeylgglt 000 250 1.8 2,3000.55 14% 445 510 662 247.2 66.1 94 27.5 1.4910 1 7 8.2g 1% obalt molbdate la 3-.--. 15.8 weight 450 250 1.0 5, 700 314+ 27 1 1 4910 0 55 86percent nickel molybdate on alum 4 do 550 250 1.0 5,700 a 27.4 1.4 .425.-.- .do 600 250 1.1 5,500 13% 27.3 1.4902 3.34 g 15 7 1 11: 000 2501.2 5,100 0.48 +3 450 500 555 248.7 66.2 94 27.3 1 4010 1 0 0.52 51silver molybdate onalum- From the results of Table I, it is apparentthat a commercial catalytic hydrogenation catalyst (catalyst A) whenused under mild conditions of 550 F. and 250 p.s.1.g. gives a productwhich is fair as far as physical +90 F.; and S, 2.1%; by treating sameby propane deasphalting, phenol extracting and methyl ethyl ketonedewaxing.

In carrying out the hydrogenation experiments in Table properties areconcerned but is ineffective in removing 70 H, the following conditionsWere sed color bodies. Similarly, cobalt molybdate ordinarily used inhydrotreating of lubricating oils, althrough being equal to commercialcatalyst A in other respects, only reduces the color to +4 /2 asdetermined by ASTM Method D-45T. Nickel molybdate, at even lower 15Temperature 550 F. Pressure 500 p.s.i.g. LVHSV 1.1. Hydrogen charge rate2,500 ftfi/bbl. Rec ery 00 TABLE II Hydrogenation of a mtcrocrystallmewax Product Characteristics,

Yield, Color, M.P. Penetration at- Total S,

Run Catalyst bb./ton ASTM .F weight (N PA) percent 7--.- 15.8 tWetightpercent nickel molybdate on alumina, prepared from aluminum 44. 1+ 17817 29 97 0.08

8- 12.2 weight percent of cobalt molybdate on alumina 4+ 179 16 27 916.7 weight percent silver molybdate on alumina 180 20 10- Catalyst B.(+219 (179) (12) (30) 11 Catalyst "8 +2 181 12 12- Alumina (alone)- +2%181 12 30 13 Activated carbon 3 180 16 29 14--. Fullers earth +2 179 1230 15 Equilibrium bauxite +2 179 19 30 16- 15.3 weight percent silvermolybdate on silica 4 177 14 27 17 25.0 weight percent copper molybdateon alumina +156 177 12 26 18 10.0 weight percent copper dichromate onpumice 4+ 177 14 24 1 Conducted at 550 F., 500 p.s.i.g., LVHSV of 1.4,Hz charge rate 2,000 ftfi/bbl. (STP), recovery 100%.

In accordance with the results of Table H, it is seen that under theconditions specified, nickel molybdate and silver molybdate areoutstanding in their ability to decolorize microcrystalline waxes. Acomparison of experiments 7 and 9 with experiment 16 shows that aluminais the best carrier for silver molybdate and nickel molybdate. Thoseproducts which have ASTM colors of +2 or 2 /z+ are not commerciallydesirable. The process of hydrogenation at low temperatures inaccordance with this invention is capable of continuous commercialproduction of 1+ color microcrystalline waxes, which is not possibleusing contacting or percolation methods.

The process of hydrogenation in accordance with this invention may beconducted on a batch or continuous basis using any type of reactor orseries of reactors known to the art. A mixture of melted wax (or thelubricating oil) and hydrogen gas is fed to the hydrogenation reactorcontaining the catalyst. This mixture is preferably preheated to thereaction temperature of 450 to 650 F. and the reactor is maintained at150 to 1000 lbs. per square inch pressure during the passage of themelted wax or lube oil therethrough. Unconsumed hydrogen is separatedfrom the products and may be recycled through the hydrogenation reactor.Hydrogen circulation rates of 800 to 4000 s.c.f/bbl. are used.

In preparing a catalystto be used in accordance with this invention, thealumina carrier may be prepared by precipitating the oxide of aluminumfrom an aqueous solution of a water-soluble aluminum salt such as thechloride, nitrate, sulfate, etc. This aqueous solution is treated withammonia, carbon dioxide or acid to precipitate an aluminum compound. Theprecipitate is washed several times with water to remove anywatersoluble impurities and then dried. The water-washing may be carriedout both before and after the drying process which is carried out at 100to 500 F. After thorough drying the prepared carrier is calcined athigher temperatures in the order of 700 to 1200 F. and may then beextruded, piiled, pelleted or otherwise shaped, granulated, or powdered.The alumina carrier is next impregnated with nickel and/ or silvermolybdate by immersing the carrier in a suitably concentrated aqueoussolution of the nickel and silver salts and ammonium molybdate. Excessunabsorbed aqueous solution is removed by decantation, filtration or bycentrifuging, and the impregnated carrier is dried at temperatures offrom 100 to 1200 F. This drying is preferably carried out in stages, asis taught in the prior art, that is, by heating to 100 to 500 F. in thefirst stage and 750 to 1200 F. in the second stage. The heating orcalcining may be accompanied by the use of an oxidizing atmospheresuitable to maintain the nickel and silver in the form of oxidesassociated or combined with the molybdena in the form known as molybdatesalts.

The catalysts may be prepared by suspension of a hydrous alumina gel indistilled water, adding aqueous solutions of water-soluble salts ofnickel and/or silver, as above mentioned, and ammonium molybdate, andprecipitating these metals from the suspension in the form of combinedoxides by adjusting the pH through the addition of a suitable base to avalue above about 7.0. The suspension is agitated during theprecipitation to bring about dispersion of the precipitated oxides inthe alumina gel. The resulting mixture is gelatinous and is waterwashedand dried, as above, to complete the catalyst preparation.

The catalysts may also be prepared by powdering an alumina carrier,calcining the powder and impregnating with water-soluble salts of nickelor silver or mixtures of same, under conditions to form nickel molybdateand/ or solver molybdate. The alumina may be activated prior toimpregnation. By each of these methods of preparation, the amount ofsilver molybdate or nickel molybdate is maintained within about 2 to 30weight percent based on the total catalyst weight. Catalysts containingabout 15.8 weight percent of nickel molybdate or about 16.7 weightpercent of silver molybdate are superior for decolorizing waxes andlubricating oils.

The foregoing complete disclosure of this invention is not to beconsidered as limiting since many variations may be made by thoseskilled in the art without departing materially from the scope or spiritof the claims:

What is claimed is:

1. The method of decolorizing a mineral lubricating oil withoutimpairing the natural resistance to oxidation and deterioration due tonaturally-occurring sulfur compounds contained therein andsimultaneously improving the steam emulsion characteristics thereofwhich consists in contacting said mineral lubricating oil with hydrogenat a temperature of about 450 to 600 F. in the presence of a catalystselected from the group of an alumina base containing about 15.8 weightpercent of nickel molybdate and an alumina base containing about 16.7weight percent of silver molybdate, and recovering a hydrogeneratedlubricating oil characterized by improved color and reduced steamemulsion number.

2. The method in accordance with claim 1 in which the temperature isabout450" F., the catalyst is an alumina base containing about 15.8weight percent of nickel molybdate.

3. The method in accordance with claim 1 in which the temperature isabout 550 F. and the catalyst is an alumina base containing about 15.8weight percent of nickel molybdate.

4. The method in accordance with claim 1 in which the temperature isabout 600 F. and the catalyst is an alumina base containing about 15.8weight percent of nickel molybdate.

5. The method in accordance with claim 1 in which the temperature isabout 600 F. and the catalyst is an alumina base containing about 16.7weight percent of silver molybdate.

, 6. The method of decolorizing a microcrystalline wax without impairingthe penetration, melting point, and natural resistance to oxidation anddeterioration due to naturally-occurring sulfur compounds containedtherein which consists in contacting said microcrystalline wax withhydrogen at a temperature of about 550 F. in the presence of a catalystselected from the group of an alumina base containing about 15.8 weightpercent of nickel molybdate and an alumina base containing about 16.7weight percent of silver molybdate, and recovering 8 a hydrogenatedmicrocrystalline wax of improved color, and having substantially thesame melting point, penetration, and content of said sulfur compounds.

References Cited in the file of this patent UNITED STATES PATENTS UNITEDSTATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 2,915,448December 1, 1959 Weldon G. Annable et al,

It is hereby certified that error appears in the -printed specificationof the above numbered patent requiring correction and that the saidLetters Patent should read as corrected below.

Column 3 and 4, Table I, fourteenth column thereof, in the sub headingunder Product Characteristics", for "V,L. read VJ, column 6,

line 37', for "solver" read silver line 61, for hydrogenerated readhydrogenated Signed and sealed this 14th day of June 1960.

( SEAL) Attest:

KARL H. AXLINE Attesting Officer ROBERT C. WATSON Commissioner ofPatents

6. THE METHOD OF DECOLORIZING A MICROCRYSTALLINE WAX WITHOUT IMPAIRINGTHE PENETRATION MELTING POINT, AND NATURAL RESISTANCE OF OXIDATION ANDDETERIORATION DUE TO NATURALLY-OCCURING SULFUR COMPOUNDS CONTAINEDTHEREIN WHICH CONSISTS IN CONTACTING SAID MICROCRYSTALLINE WAX WITHHYDROGEN AT A TEMPERATURE OF ABOUT 550*F. IN THE PRESENCE OF A CATALYSTSELECTED FROM THE GROUP OF AN ALUMINA BASE CONTAINING ABOUT 15.8 WEIGHTPERCENT OF NICKEL MOLYBDATE AND AN ALUMINA BASE CONTAINING ABOUT 16.7WEIGHT PERCENT OF SILVER MOLYBDATE, AND RECOVERING A HYDROGENATEDMICROCRYSTALLINE WAX OF IMPROVED COLOR, AND HAVING SUBSTANTIALLY THESAME MELTING POINT, PENETRATION, AND CONTENT OF SAID SULFUR COMPOUNDS.